// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_VIEWS_PAINTER_H_
#define UI_VIEWS_PAINTER_H_

#include <stddef.h>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/base/nine_image_painter_factory.h"
#include "ui/views/views_export.h"

namespace gfx {
class Canvas;
class ImageSkia;
class Insets;
class Rect;
class Size;
}

namespace views {

class View;

// Painter, as the name implies, is responsible for painting in a particular
// region. Think of Painter as a Border or Background that can be painted
// in any region of a View.
class VIEWS_EXPORT Painter {
public:
    Painter();
    virtual ~Painter();

    // A convenience method for painting a Painter in a particular region.
    // This translates the canvas to x/y and paints the painter.
    static void PaintPainterAt(gfx::Canvas* canvas,
        Painter* painter,
        const gfx::Rect& rect);

    // Convenience that paints |focus_painter| only if |view| HasFocus() and
    // |focus_painter| is non-NULL.
    static void PaintFocusPainter(View* view,
        gfx::Canvas* canvas,
        Painter* focus_painter);

    // Creates a painter that draws a gradient between the two colors.
    static Painter* CreateHorizontalGradient(SkColor c1, SkColor c2);
    static Painter* CreateVerticalGradient(SkColor c1, SkColor c2);

    // Creates a painter that draws a multi-color gradient. |colors| contains the
    // gradient colors and |pos| the relative positions of the colors. The first
    // element in |pos| must be 0.0 and the last element 1.0. |count| contains
    // the number of elements in |colors| and |pos|.
    static Painter* CreateVerticalMultiColorGradient(SkColor* colors,
        SkScalar* pos,
        size_t count);

    // Creates a painter that divides |image| into nine regions. The four corners
    // are rendered at the size specified in insets (eg. the upper-left corner is
    // rendered at 0 x 0 with a size of insets.left() x insets.top()). The center
    // and edge images are stretched to fill the painted area.
    static Painter* CreateImagePainter(const gfx::ImageSkia& image,
        const gfx::Insets& insets);

    // Creates a painter that paints images in a scalable grid. The images must
    // share widths by column and heights by row. The corners are painted at full
    // size, while center and edge images are stretched to fill the painted area.
    // The center image may be zero (to be skipped). This ordering must be used:
    // Top-Left/Top/Top-Right/Left/[Center]/Right/Bottom-Left/Bottom/Bottom-Right.
    static Painter* CreateImageGridPainter(const int image_ids[]);

    // Factory methods for creating painters intended for rendering focus.
    static scoped_ptr<Painter> CreateDashedFocusPainter();
    static scoped_ptr<Painter> CreateDashedFocusPainterWithInsets(
        const gfx::Insets& insets);
    static scoped_ptr<Painter> CreateSolidFocusPainter(SkColor color,
        const gfx::Insets& insets);

    // Returns the minimum size this painter can paint without obvious graphical
    // problems (e.g. overlapping images).
    virtual gfx::Size GetMinimumSize() const = 0;

    // Paints the painter in the specified region.
    virtual void Paint(gfx::Canvas* canvas, const gfx::Size& size) = 0;

private:
    DISALLOW_COPY_AND_ASSIGN(Painter);
};

// HorizontalPainter paints 3 images into a box: left, center and right. The
// left and right images are drawn to size at the left/right edges of the
// region. The center is tiled in the remaining space. All images must have the
// same height.
class VIEWS_EXPORT HorizontalPainter : public Painter {
public:
    // Constructs a new HorizontalPainter loading the specified image names.
    // The images must be in the order left, right and center.
    explicit HorizontalPainter(const int image_resource_names[]);
    ~HorizontalPainter() override;

    // Painter:
    gfx::Size GetMinimumSize() const override;
    void Paint(gfx::Canvas* canvas, const gfx::Size& size) override;

private:
    // The image chunks.
    enum BorderElements {
        LEFT,
        CENTER,
        RIGHT
    };

    // NOTE: the images are owned by ResourceBundle. Don't free them.
    const gfx::ImageSkia* images_[3];

    DISALLOW_COPY_AND_ASSIGN(HorizontalPainter);
};

} // namespace views

#endif // UI_VIEWS_PAINTER_H_
